WARNING
WARNING TO SERVICE PERSONS! Electric shock hazard. When electrical power to the internal control box components must be available for troubleshooting, a common practice is to construct a ass" of the door interlock switch. When such a by−pass is in place, a potential shock hazard is present which can cause injury or death. Make sure any door interlock switch by−pass has been removed after troubleshooting is complete and BEFORE attempting any re- pairs to the control box components!
Troubleshooting: Heating Sequence of Operation
CONDITIONS:
Power On
Normal Operation LED: Steady Flash
Thermostat (S1) Calls for Heat
YES
Fixed blower−ON delay (45−second) complete
NO
Check for 24 Volts Between W and C at A52 Terminal Strip
Blower Operates at the Heating Speed Selected by HEAT Jumper and ADJUST Jumper Positions on the BDC3 Control (A52)
YES 
CFM Light on A52 Indicates Blower
Speed Selection with 100CFM / Blink
YES
Thermostat (S1) Demand Satisfied
YES
30 Second Blower Off Delay (Fixed) Complete
YES
Demand for Heat Satisfied
NO
Check for 24 Volts Between Pins 3 and 2 on J49
Page 20
505047 09/06
